“More than one half of an average person’s day is spent being sedentary — sitting, watching television, or working at a computer,” said Dr. David Alter, Senior Scientist at the University Health Network (UHN) and Institute for Clinical Evaluative Sciences. “Our study finds that despite the health-enhancing benefits of physical activity, this alone may not be enough to reduce the risk for disease.”

To reach their conclusions, Dr. Alter’s team conducted a systematic review and meta-analysis of published research focusing on the health effects of sedentary time.

While sitting time was associated with adverse health outcomes and premature mortality even among people who exercised, the negative effects were more pronounced among those who did little or no exercise compared to those who participated in higher amounts of exercise, the researchers found.

“The findings suggest that the health risk of sitting too much is less pronounced when physical activity is increased,” said Avi Biswas, the lead author and a PhD candidate from the Institute of Health Policy, Management and Evaluation at the University of Toronto. “We need further research to better understand how much physical activity is needed to offset the health risks associated with long sedentary time and optimize our health.”

Future research will help determine what interventions, in addition to physical activity, are effective against the health risks of sedentary time, the researchers said.

“Avoiding sedentary time and getting regular exercise are both important for improving your health and survival,” said Dr. Alter. “It is not good enough to exercise for 30 minutes a day and be sedentary for 23 and half hours.” In the interim, he says there are a number of strategies people can use to reduce sitting time.

“The first step is to monitor sitting times — once we start counting, we’re more likely to change our behavior,” said Dr. Alter. “Next is setting achievable goals and finding opportunities to incorporate greater physical activity — and less time sitting — into your daily life.”

He offers simple steps for becoming less sedentary, such as taking a 1-3 minute break every half hour or so throughout the day to stand (standing burns twice as many calories as sitting) or moving around at work. Standing or exercising while watching television can also help. The target, he says, is to decrease sedentary time by two to three hours in a 12-hour day.